A rectangle is $5$ centimeters long. The rectangle is also $4$ centimeters wide. What is its perimeter?
Solution: $5\text{ cm}$ $4\text{ cm}$ The perimeter is the total length of all the sides of the shape added together. Add up the lengths of the sides: $ \text{perimeter} = {4} + {5} + {4} + {5} $ $ \text{perimeter} = 18\text{ cm} $